Solution mining method and apparatus

ABSTRACT

A method of solution mining soluble subterranean deposits is shown in which a bore hole is cased to the depth equivalent to a desired height of a cavity to be developed in a deposit. Into the cased bore hole a tubing string is introduced with a liner rigidly mounted thereon. The tubing is passed through the casing and into the soluble deposit a substantial distance below the end of the casing set in the deposit. A fixed distance is provided between the end of the tubing and the end of the liner attached thereto. Solvent is then introduced into the soluble deposit and cavity development begun by dissolution of the minerals in the deposit with a suitable solvent. When lateral development of the cavity has proceeded to the desired extent, roof raises are made by moving the tubing string in a vertical direction upward from ground level. The fixed liner moves with the tubing string since it is rigidly mounted thereto. Thus, a fixed mining distance is maintained between the influent point for the solvent entering the soluble deposit and the effluent or withdrawal point. Roof raises can be accomplished in this manner as fixed distances until the liner is finally introduced into the casing by the vertical movement of the tubing toward the ground surface. The apparatus involved in conducting the novel method of the invention is also disclosed.

United States Patent Primary Examiner-Ernest R. Purser Attorney-Chisholm& Spencer ABSTRACT: A method of solution mining soluble subterraneandeposits is shown in which a bore hole is cased to the depth equivalentto a desired height of a cavity to be developed in a deposit. Into thecased bore hole a tubing string is introduced with a liner rigidlymounted thereon. The tubing is passed through the casing and into thesoluble deposit a substantial distance below the end of the casing setin the deposit. A fixed distance is provided between the end of thetubing and the end of the liner attached thereto. Solvent is thenintroduced into the soluble deposit and cavity development begun bydissolution of the minerals in the deposit with a suitable solvent. Whenlateral development of the cavity has proceeded to the desired extent,roof raises are made by moving the tubing string in a vertical directionupward from ground level. The fixed liner moves with the tubing stringsince it is rigidly mounted thereto. Thus, a fixed mining distance ismaintained between the influent point for the solvent entering thesoluble deposit and the efiluent or withdrawal point. Roof raises can beaccomplished in this manner as fixed distances until the liner isfinally introduced into the casing by the vertical movement of thetubing toward the ground surface. The apparatus involved in conductingthe novel method of the invention is also disclosed.

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" FIGS PATENTED MAY 1- 8 1971 SHEET Q [If 4 WAW/A F 7 INVENTORY BYRON e50M ouos DOUGLAS 0. e055 A ORNEYS SOLUTION MINING METHOD AND APPARATUSBACKGROUND OF THE INVENTION Many methods have been employed in the pastfor developing cavities in salt or other soluble rock. Representative ofthe recent patents issued in this area are U.S. Pat. Nos. 2,787,455,3,277,654 and 3,088,717. As disclosed in these patents, various methodsare employed for adjusting tubing strings and tailpipe liners indeveloping well cavities. These prior art methods, however, provide forindependent movement of tubing strings and liners which is undesirablewhere it is desired that a fixed distance be maintained between theinfluent for solvent and the effluent for dissolved material from asolution mining cavity. The inability to precisely determine theposition of the liner or the tailpipe or tubing in a subterranean cavitylocated several thousand feet below ground makes it extremely difficultto precisely determine the extent to which a roof raise will be taken.Furthermore, in developing large cavities in soluble salt deposits. whenroof raises are made it is frequently necessary that the tubing bepulled from the hole in order that the casing can be perforated during aroof raise. This latter procedure, of course, requires a considerableamount of development time within a given solution mining cavity for thetubing string to be pulled and for the devices to be set in the casingfor the necessary perforation.

THE INVENTION In accordance with the instant invention, mining heightmay remain constant during the solution mining of a subterranean cavityand the tubing does not have to be pulled from the hole to perforatecasings in order to make a roof raise in a development cavity. By virtueof the instant invention, a constant mining height is maintained, thatis the influent and effluent points are a fixed vertical distance fromeach other, and since the tubing goes completely through the liner andis firmly and rigidly affixed to the lining, it is only necessary thatthe tubing be raised in order to make a roof raise in a developmentcavity thereby minimizing development time since the necessity ofremoving drill strings to perforate casing is avoided.

The invention will be more readily understood by reference to theaccompanying drawing in which:

FIGS. ll, 2, 3, 4 and of the accompanying drawing show a diagrammaticillustration of the method ofthe instant invention as applied to thesolution mining of a KCI deposit having NaCl present therein,

FIG. 6 is illustrative of suitable apparatus to accomplish the method ofsolution mining disclosed, and

FIG. 7 illustrates the method of the instant invention appliedto twointerconnected cavities.

As shown in FIG. 1, a bore hole 1 is drilled to a point near the bottomof a KCl rich-NaCl lean deposit located beneath a KCl rich-NaCl leandeposit which is to be mined. The bore hole I is cased to the upper faceof the KCl rich-NaCl lean deposit with casing member 2 utilizingconventional casing techniques. The casing is then utilized to pass adrill pipe or tube 3 down into the deposit 4 rich in KCl' and lean inNaCl, through that deposit and into a KCl lean-NaCl rich deposit 5. Thetube 3 is positioned in the deposit 5 near the bottom thereof.Associated with the tube 3 and rigidly attached thereto is a liner 6.This liner is long enough to reach from the casing to a point above theend of. the tube member 3. The distance between the end of the liner 6and the tube 3 is fixed at the desired distance for solution mining thedeposit to be worked. Solution, typically water or weak brine, is thenpreferably introduced into the liner member 6 in annular space 8 andinto the deposit 5 and solution mining of the NaCl rich-KC] lean depositbegins. The dissolved sodium chloridepotassium chloride is removedthrough the tube 3 and passed to the surface of the ground where it maybe discarded, processed for its NaCl content or utilized as feed solventto KC] rich-NaCl lean deposit.

A suitable cavity is then developed in the deposit in a lateral as wellas vertical direction. Lateral development in the deposit may beaccomplished by oil or gas padding the roof of the cavity oncedevelopment has begun. This is readily accomplished, for example, byfeeding a liquid immiscible with brine solution to the cavity. Anyliquid immiscible with brine and having a density less than the cavitysolution may be employed to provide a layer of protective liquid 10 onthe roof of the cavity (See FIG. 5). In similar fashion, a liquidimmiscible with cavity liquor and having a density greater than thecavity solution can be introduced with the solvent to provide a liquidpad 11 on the floor of the cavity. Obviously, both padding liquidsshould be such that they do not solubilize the material being mined. Inthis manner, the initial cavity can be developed in a lateral directionfor a substantial distance. Typically, hydrocarbon oils, chlorinatedorganics and other like materials are utilized for padding purposes.

In FIG. 2, a cavity 7 which has been developed in a lateral directionfor some distance has been formed'in the NaCl rich- KCl lean deposit.The tube 3 and its associated liner have been raised so that the end ofthe liner is now resting on the interface 9 of the deposits 5 and 4.Solution is continuously introduced through liner 6 to the cavity 7 andwith further padding the cavity is extended in a lateral direction for asubstantial distance preparatory to mining the KC] rich-NaCl lean strata4 located above the cavity 7.

I In FIG. 3, the tube 3 and liner 6 have been moved vertically throughthe NaCl rich-KCI lean deposit. The end of the tube 3 is now located atthe base of the KC] rich-NaCl lean deposit and the end of the liner 6 ispositioned inside the KCl rich- NaCl lean deposit. Solution fordissolution of the KCI rich- NaCl lean deposit is continuouslyintroduced into the deposit and dissolution of the KC] rich-NaCl leandeposit takes place. The lateral extent of the cavity formed ispreferably maintained the same as that established in the NaCl rich-KCLlean deposit in the final roof raise in that deposit and the cavity 7 isnow expanded in the vertical direction through the KCI rich- NaCl leandeposit. Solution introduced into the cavity 7 through the liner 6 isremoved with dissolved minerals through the tube 3.

FIG. 4 depicts the raising of the roof of the cavity 7 in the KClrich-NaCl lean deposit by a further movement of the tube 3 and theattached liner 6 upward in the deposit 4. Once again preferably thelateral confines of the cavity are maintained the same and the depositis mined vertically until the roof of the cavity with the desiredlateral dimension reaches the end of the liner 6. Solution is preferablyintroduced to the cavity 7 and exits through annular space 8 to thesurface. Lateral development takes place by roof padding in theconventional manner.

FIG. 5 shows the final roof raise of the cavity 7 to the end of thepermanent casing member 2. Once again, the tube 3 and the associatedliner 6 have been raised vertically into the casing so that the end ofthe liner 6 is now within the casing 2.

Tube 3 is still within the cavity and is utilized to remove productfluid therefrom. The incoming solvent for the cavity 7 passes in space 8through liner 6.

' FIG. 6 shows the apparatus of the instant invention positioned in acasing at its upper end with the tube 3 positioned in the cavity 7 andthe associated liner positioned in casing 2. In this apparatus, the tube3 passes through the liner member 6 and the end of the tube 3 in thecavity 7 is positioned a fixed distance below the one end of liner 6.The liner 6 is rigidly mounted to the tube 3 by means of a spiderconnection 13 at the base and a similar connection 14 located beneath aliner joint 15. Positioned above the joint 15 is a mandrel packer cup16. The mandrel packer cup seals the liner assembly against the casing 2and thus fluid will not flow through the liner above this point. Fluid,leaving the cavity may be passed up through the annulus formed by theouter wall of the tube 3 and the inside wall of the liner 6 though inpreferred operation this annulus is used for feed solution to thecavity. The spider connections l3 and 14 can conveniently consist ofmetal rods, bars, braces and the like which are welded to the outside ofthe tube 3 and the inside wall of the liner 6. The number and placementof these elements is discretionary, the only important considerationbeing that they be so arranged that fluid flow through the liner is notprevented. While normal flow to the cavity is for solvent to enter vialiner 6 and the annulus 8 and leave via tube 3, once the solution miningcavity is established the flow can be reversed so that the tube 3 servesas the feed conduit and the annulus 8 as the product solution removalconduit.

The exact distance between the end of the liner 6 and the end of thetube 3 that is maintained may be varied considerably without departingfrom the spirit of the invention. This distance will be detennined bythe deposit in which it is desired to employ the invention and thenumber of roof raises that are desired in developing a cavity in thatdeposit. In formations where considerable roof collapsing isanticipated, it might be determined that a multiplicity of roof raisesare desired prior to establishing the final cavity mining width. In suchan instance, the use of a small mining height 2 to feet may be desired.If this should be the case, the liner and tube are fixed so that thedistance between their end points in the cavity are within thisspecified range. In other deposits, the use of greater mining heightsand a smaller number of roof raises may be desired. In this case, ofcourse, the mining height is increased accordingly by providing a largerdistance between the end ofthe liner 6 in the cavity and the end of thetube 3 in the cavity.

In FIG. 7 the use of the instant invention is depicted in a preferredembodiment utilized in the solution mining of multiple cavities. Asshown in FIG. 7, two cavities 7 and 7 have been established in a KCllean-NaCl rich deposit and by lateral development these cavities havebeen connected at and 10. The liner 6' and its connected tube 3' ismoved vertically into deposit 4 which is KCl rich-NaCl lean. Solventflows into the deposit 4' through annulus 8 and dissolution of the KClrich-NaCl lean deposit is begun. The product fluid is removed preferablythrough annulus 8 of the liner 6 placed in the cavity 7. In thisoperation the tube 3 can be plugged to prevent flow therethrough. Whenthe mining of deposit 4 has proceeded to the desired extent the tube 3and liner 6 of cavity 7 may be moved upwardly in deposit 4 and liquidflow reversed so that solvent is now introduced via annulus 8 to thedeposit 4 and product solution is recovered via annulus 8' from thecavity 7. As has been previously stated while it is preferable to employthe annulus 8 or 8' for solvent flow into a deposit the tube 3 can beemployed for this purpose.

As will be readily understood the instant invention can be employed todevelop a cavity in a KCl lean-NaCl rich deposit positioned adjacent alarge cavity located in a KCl rich-NaCl lean deposit to laterallycommunicate with the cavity through the KO lean-NaCl rich zone. The tubeand liner can then be raised in increments to mine the KCl rich-NaCllean deposit above the KC] lean-NaCl rich zone by operating the existingcavity as a withdrawal cavity for the KCl dissolved as the KCl rich-NaCllean deposit is mined during movement of the tube and liner verticallythrough the deposit.

In discussing the invention, particular emphasis has been made to thesolution mining of KCl. This has been only for the purposeofillustration. Indeed, the method described for mining a specific typeof KCl deposit has been given as a preferred mode of mining such adeposit. This same deposit can be mined differently with the method ofthe instant invention without departing from the inventive concept.

Thus, the initial cavity in a KC] rich-NaCl lean deposit can be formedin that deposit, if desired, instead of in the NaCl rich-KCl leandeposit below it as depicted in FIGS. 1 through 5. In such an operation.the method utilized is essentially the same as described above. The tube3 and its liner 6 are placed in the deposit through borehole I and thecasing 2 to the desired depth and the solvent is introduced through tube3 to solubilize the minerals in the deposit. The cavity solutioncontaining the minerals is removed through the liner 6 between the outerwall of tube 3 and the inner wall of the liner 6. Lateral development ofthe cavity is undertaken as described above by suitably protecting thefloor and roof of the cavity preferably with an inert liquid. Ifdesired, an inert solid can be employed on the floor. Gas padding of theroof in lieu of liquid padding is also within our contemplation. The useof a liquid padding of a cavity roof is described in U.S. Pat. No.3,096,969 and the method described therein is suitable for use inassociation with the development of solution mining cavities using theinstant invention. The use of solid inerts to protect cavity floor issimilarly described in U.S. Pat. No. 3,339,978. Obviously, inert liquidsheavier than the cavity solution, can also be employed for floorprotection. Maintaining a saturated brine not capable of dissolving anyfurther scale at the cavity floor will also serve adequately asprotection and permit lateral development.

' Once the cavity has been extended laterally in the KCl rich- NaCl leandeposit the desired distance, the tube 3 is moved in a verticaldirection the desired distance and further development of the cavity ina vertical and, if desired, lateral direction can take place.

In a further embodiment of the instant invention the bore hole 1 may becased to the interface 9 between deposits 4 and 5 depicted in FIG. 1. Inthis instance the roof raises are taken in the same manner as depictedin FIGS. 1, land 3 until the cavity is in communication with the casingmember 1. At this point the casing may be used during the mining of theKC] rich-NaCl lean deposit. By conventional perforation techniques thecasing may be perforated, the tubing string with the associated linermay be removed and a tube introduced into the bore hole for theintroduction of solvent. Solution mining of the KCl-n'ch zone can thenproceed in the conventional manner employed with casing permanentlyaffixed in a minable deposit. This further method may be desirable wherea communication with a second cavity has been established during thedevelopment of the cavity in the NaCl rich-KCl lean deposit and bothcavities are being used in the mining operation. In this latter instanceone of the cavities is typically utilized as the solvent introductionpoint for mining the KCl rich-NaCl lean deposit while the second cavityis employed as the withdrawal zone for the KCl product mineral. Duringoperation of multiple cavities of this nature, flow may be reversed fromtime to time so that a cavity may serve to receive fresh solvent at onetime and be utilized to remove product another time.

The ease with which a roof raise can be made utilizing the inventionconcept herein described can be readily appreciated. '1" he costlyprocedures formerly employed of perforating casings during cavitydevelopment stages of solution mining is eliminated. A constant miningheight may now be maintained by vertical adjustment from ground level ofthe tubing 3 both during development stages of a solution miningoperation as well as during development of the product cavity. Theapparatus employed can be simply constructed to accomplish the methoddescribed and a considerable reduction in the time normally required todevelop a solution mining cavity and the consequent saving in costsreadily realized.

As used herein in the specification and claims, KCl rich- NaCl leandeposit refers to deposits of KCl and NaCl containing 15 to 60 percentKCl based on the total weight of KCl and NaCl in the deposit. KCllean-NaCl rich deposits refer to deposits which contain less than 15percent KCl by weight of the NaCl and KCl therein or which contain nosubstantial amount of KCl but which are predominantly sodium chloride.

It will be apparent that the method described can be utilized in anysolution mining operation involving the dissolution of mineral depositssuch as sodium chloride, potassium chloride, magnesium chloride and thelike. Thus, while the invention has been described with specificreference to KCl mineral deposits, it is not intended that the methodand apparatus be so limited. .So long as a mineral deposit can be minedby solution mining techniques, the method and apparatus herein describedmay be employed and the advantages obtained. Therefore, it is notintended that the invention be limited to a ing claims.

We claim:

1 l. A method of solution mining a soluble subterranean depositcomprising drilling a borehole into a subterranean deposit, casing saidborehole to a depth equivalent to a desired height for a cavity to bedeveloped in said deposit, introducing into said casing a tubing stringwith a liner rigidly mounted thereon, said tubing string passing throughsaid liner, continuing the introduction of said tubing through thecasing and into the soluble deposit to be mined a substantial distancebelow the end of said casing while maintaining the liner within saidcasing at one end thereof and a substantial distance below the casing atthe other end thereof, providing a fixed distance between the end of thetubing and the end of the liner positioned in the deposit, introducingsolvent into the deposit through the liner and removing dissolvedminerals through the tubing to thereby form a cavity and adjusting theheight of the cavity by moving the tubing vertically away from thecavity to thereby move the liner rigidly mounted thereto the samedistance that the tubing is moved.

2. A method of initiating cavity development in a solution mining cavitycomprising positioning a fluid conduit for influent solvent in a desiredlocation in a soluble deposit, positi'oning a second conduit foreffluent in said soluble deposit at a fixed distance from said influentconduit, said conduits being affixed to each other and one conduitsurrounding at least a portion of the other conduit, the ends of bothconduits being a fixed distance from each other, introducing solventthrough the conduit for influent solvent capable of dissolving saidsoluble deposit, removing solution from said second conduit, to therebyestablish a cavity in said soluble deposit, repositioning both of saidconduits when the cavity has reached a predetermined size by raising oneof said conduits to thereby increase the height of the roof of saidcavity and to thereby raise the other conduit afiixed to the one whichis raised.

3. A method of developing a solution mining cavity in a subterraneanmineral deposit comprising boring a hole into said deposit, casing saiddeposit at a desired height for a solution mining cavity to bedeveloped, introducing through said casing at least two fluid conduitsrigidly affixed to each other so that when one conduit is moved in avertical direction the other conduit must move with it, one of saidconduits being circumferentially disposed around at least a part of theother conduit, the lower end of said two conduits being spaced a fixeddistance from each other, positioning the lower ends of both conduits asubstantial distance below the end of said casing, introducing fluidcapable of dissolving the mineral content of the said deposit into theouter conduit and withdrawing product solution from the inner conduit,developing a cavity by dissolution of minerals in a lateral direction toa desired distance, raising both of said conduits simultaneously to ahigher level in said deposit while maintaining the distance betweentheir lower ends constant by raising one of the con duits, dissolvingfurther quantities of minerals at the new position of said conduitsuntil the desired mineral content has been removed from said deposit inthe new position.

4. Apparatus for developing a solution mining cavity comprising a firstfluid conduit, a second fluid conduit having a diameter greater thansaid first ,fluid conduit, means for mounting said second conduit in afixed engagement to said first conduit to thereby form a unit wherebyone conduit cannot be moved without the other conduit being moved, bothconduits being constructed and arranged so as to be capable of beingpassed into a cased borehole, means associated with said second conduitto seal said conduit to a borehole casing, said first and secondconduits being spaced from each other in a vertical direction to providea fixed distance between their lower ends when positioned in a borehole.

5. A method of solution mining a soluble subterranean deposit comprisingdrilling a borehole into a subterranean deposit, casing said borehole toa depth equivalent to a desired height for a cavity to be developed insaid deposit, introducing into said casing tubing having a liner rigidlyaffixed thereto so that the liner moves when said tubing moves, theliner and tubing being so arranged in fixed relationship that the lowerends of each terminate at a fixed distance from each other therebyproviding a vertical mining height between their ends, passing the saidtubing through the said casing and into the soluble deposit whilemaintaining at least a portion of the attached liner within said casing,introducing solvent for the minerals in said deposit into the liner andremoving dissolved minerals through said tubing.

6. A method of solution mining a KC] rich-NaCl lean deposit positionedabove a KC] lean-NaCl rich deposit, comprising providing a boreholethrough said KC] rich-NaCl lean deposit and into said KCl lean-NaCl richdeposit, casing said borehole to at least the upper portion of said KC]rich-NaC] lean deposit, introducing through said casing a tube havingrigidly mounted thereto a liner defining a conduit between its innerwall and the outer wall of said tube, the tube and liner being soarranged in their mounting relationship that the end of the tube is afixed vertical distance below the end of said liner, positioning theends of the tube and liner in said KC] lean-NaCl rich deposit whilemaintaining a portion of the liner within said casing, introducingsolvent into said KC] lean-NaCl rich deposit through said liner andremoving solution through said tube to thereby form a cavity in the KC]lean-NaCl rich deposit, developing said cavity to a desired lateraldistance, moving said tube and thereby moving its associated linerupwardly when the cavity has developed the desired lateral distance,continuing dissolution of the KC] lean-NaCl rich deposit while the tubeand liner are in their new position to a desired lateral distance, andcontinuing the raising of the tube and liner and lateral cavitydevelopment in this manner until the end of the tube is positionedwithin the KCl rich-NaCl lean deposit.

7. A method of solution mining KC] from a KC] rich-NaCl lean depositlocated above a KCl lean-NaCl rich deposit comprising drilling aborehole through said KCl rich-NaCl lean deposit and into said KC]lean-NaCl rich deposit, casing said borehole to a point near the uppersurface of said KC] rich- NaCl lean deposit, passing a tube having aliner fixedly attached thereto through the cased borehole a sufficientdistance to thereby position the lower ends of both the tube and theassociated liner in the KC] lean-NaCl rich deposit while positioning theupper end of the liner inside the casing, the tube and liner being soarranged that the end of the tube is positioned below the end of theliner in said deposit a fixed distance, introducing a solvent suitablefor dissolution of the mineral content of said KC] lean-NaC] richdeposit through the liner to thereby dissolve the minerals in'said KC]lean- NaCl rich deposit, withdrawing dissolved minerals through saidtube, laterally developing a cavity in said KC] lean-NaCl rich depositto a desired degree, increasing the height of the cavity so developed byraising the tube vertically in increments and thereby raising itsassociated liner the same increments to thereby ultimately extend thecavity into said KC] rich-NaCl lean deposit, and recovering the mineralcontent of the KC] rich-NaCl lean deposit as a solution through saidtube.

8. The method of claim 7 wherein said borehole is cased to a point nearthe interface between said KC] rich-NaCl lean deposit and said KC]lean-NaCl rich deposit.

9. The method of claim 7 wherein the initial cavity is developed in alateral direction by padding the roof of the cavity with a fluidimmiscible with the cavity solution.

10. The method of claim 7 wherein said solvent is introduced throughsaid tube and the said dissolved minerals are withdrawn through saidliner.

1]. A method of solution mining KC] from a KC] rich-NaC] lean depositpositioned above a KC] lean-NaCl rich deposit wherein a first cavity ispositioned adjacent said KCl lean- NaCl rich deposit comprising drillinga borehole into said KC] lean-NaCl rich deposit adjacent to said firstcavity, casing the borehole to at least the top of the KC] rich-NaCllean deposit, passing a tube having a liner fixedly mounted thereto andaround said tube through said borehole a sufficient distance to positionthe lower ends of both the tube and the liner in the KC] lean-NaCl richdeposit while maintaining the upper end of the liner inside of saidcasing, the tube and liner being so arranged that their lower ends arespaced apart from each other a fixed distance, introducing solventsuitable for dissolution of the mineral content of said KCl lean-NaClrich deposit through the liner to thereby dissolve the minerals in saiddeposit, withdrawing dissolved minerals through said tube, laterallydeveloping a cavity in said KC] lean-NaCl rich deposit until the cavitybeing developed communicates with said first cavity, withdrawingdissolved minerals from said first cavity when the cavity beingdeveloped communicates therewith while using the cavity being developedas an injection cavity for solvent, periodically raising the tube andthereby raising the associated liner in the cavity being developed afixed distance to increase the height of the said injection cavity,continuing the dissolution of the mineral con tent of the KCl lean-NaClrich deposit, continuing periodic raising of the tube and thereby theliner until the ends of the tube and liner are in the KO rich-NaCl leandeposit and dissolving the mineral content of the KCl rich-NaCl leandeposit.

12. The method of claim 11 wherein the flow of solvent in the twocavities is reversed so that solvent flows into the existing cavity anddissolved minerals are withdrawn from said cavity being developed.

223 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,578,808 Dated May 18, 1971 lnvenunis) yron P. Edmonds and Douglas C.Ruse It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

In the heading, ssignee's name Kolium" should be "Kalium" Signed andsealed this 31st day of August 1971.

(SEAL) Attest:

EDWARD MFLETGHER JR. ROBERT GOTTSCI IALK Attesting gfficer ActingCommissioner of Patents

1. A method of solution mining a soluble subterranean deposit comprisingdrilling a borehole into a subterranean deposit, casing said borehole toa depth equivalent to a desired height for a cavity to be developed insaid deposit, introducing into said casing a tubing string with a linerrigidly mounted thereon, said tubing string passing through said liner,continuing the introduction of said tubing through the casing and intothe soluble deposit to be mined a substantial distance below the end ofsaid casing while maintaining the liner within said casing at one endthereof and a substantial distance below the casing at the other endthereof, providing a fixed distance between the end of tHe tubing andthe end of the liner positioned in the deposit, introducing solvent intothe deposit through the liner and removing dissolved minerals throughthe tubing to thereby form a cavity and adjusting the height of thecavity by moving the tubing vertically away from the cavity to therebymove the liner rigidly mounted thereto the same distance that the tubingis moved.
 2. A method of initiating cavity development in a solutionmining cavity comprising positioning a fluid conduit for influentsolvent in a desired location in a soluble deposit, positioning a secondconduit for effluent in said soluble deposit at a fixed distance fromsaid influent conduit, said conduits being affixed to each other and oneconduit surrounding at least a portion of the other conduit, the ends ofboth conduits being a fixed distance from each other, introducingsolvent through the conduit for influent solvent capable of dissolvingsaid soluble deposit, removing solution from said second conduit, tothereby establish a cavity in said soluble deposit, repositioning bothof said conduits when the cavity has reached a predetermined size byraising one of said conduits to thereby increase the height of the roofof said cavity and to thereby raise the other conduit affixed to the onewhich is raised.
 3. A method of developing a solution mining cavity in asubterranean mineral deposit comprising boring a hole into said deposit,casing said deposit at a desired height for a solution mining cavity tobe developed, introducing through said casing at least two fluidconduits rigidly affixed to each other so that when one conduit is movedin a vertical direction the other conduit must move with it, one of saidconduits being circumferentially disposed around at least a part of theother conduit, the lower end of said two conduits being spaced a fixeddistance from each other, positioning the lower ends of both conduits asubstantial distance below the end of said casing, introducing fluidcapable of dissolving the mineral content of the said deposit into theouter conduit and withdrawing product solution from the inner conduit,developing a cavity by dissolution of minerals in a lateral direction toa desired distance, raising both of said conduits simultaneously to ahigher level in said deposit while maintaining the distance betweentheir lower ends constant by raising one of the conduits, dissolvingfurther quantities of minerals at the new position of said conduitsuntil the desired mineral content has been removed from said deposit inthe new position.
 4. Apparatus for developing a solution mining cavitycomprising a first fluid conduit, a second fluid conduit having adiameter greater than said first fluid conduit, means for mounting saidsecond conduit in a fixed engagement to said first conduit to therebyform a unit whereby one conduit cannot be moved without the otherconduit being moved, both conduits being constructed and arranged so asto be capable of being passed into a cased borehole, means associatedwith said second conduit to seal said conduit to a borehole casing, saidfirst and second conduits being spaced from each other in a verticaldirection to provide a fixed distance between their lower ends whenpositioned in a borehole.
 5. A method of solution mining a solublesubterranean deposit comprising drilling a borehole into a subterraneandeposit, casing said borehole to a depth equivalent to a desired heightfor a cavity to be developed in said deposit, introducing into saidcasing tubing having a liner rigidly affixed thereto so that the linermoves when said tubing moves, the liner and tubing being so arranged infixed relationship that the lower ends of each terminate at a fixeddistance from each other thereby providing a vertical mining heightbetween their ends, passing the said tubing through the said casing andinto the soluble deposit while maintaining at least a portion of theattached liner within said casing, introducing solvent for the mineralsin said dePosit into the liner and removing dissolved minerals throughsaid tubing.
 6. A method of solution mining a KCl rich-NaCl lean depositpositioned above a KCl lean-NaCl rich deposit, comprising providing aborehole through said KCl rich-NaCl lean deposit and into said KCllean-NaCl rich deposit, casing said borehole to at least the upperportion of said KCl rich-NaCl lean deposit, introducing through saidcasing a tube having rigidly mounted thereto a liner defining a conduitbetween its inner wall and the outer wall of said tube, the tube andliner being so arranged in their mounting relationship that the end ofthe tube is a fixed vertical distance below the end of said liner,positioning the ends of the tube and liner in said KCl lean-NaCl richdeposit while maintaining a portion of the liner within said casing,introducing solvent into said KCl lean-NaCl rich deposit through saidliner and removing solution through said tube to thereby form a cavityin the KCl lean-NaCl rich deposit, developing said cavity to a desiredlateral distance, moving said tube and thereby moving its associatedliner upwardly when the cavity has developed the desired lateraldistance, continuing dissolution of the KCl lean-NaCl rich deposit whilethe tube and liner are in their new position to a desired lateraldistance, and continuing the raising of the tube and liner and lateralcavity development in this manner until the end of the tube ispositioned within the KCl rich-NaCl lean deposit.
 7. A method ofsolution mining KCl from a KCl rich-NaCl lean deposit located above aKCl lean-NaCl rich deposit comprising drilling a borehole through saidKCl rich-NaCl lean deposit and into said KCl lean-NaCl rich deposit,casing said borehole to a point near the upper surface of said KClrich-NaCl lean deposit, passing a tube having a liner fixedly attachedthereto through the cased borehole a sufficient distance to therebyposition the lower ends of both the tube and the associated liner in theKCl lean-NaCl rich deposit while positioning the upper end of the linerinside the casing, the tube and liner being so arranged that the end ofthe tube is positioned below the end of the liner in said deposit afixed distance, introducing a solvent suitable for dissolution of themineral content of said KCl lean-NaCl rich deposit through the liner tothereby dissolve the minerals in said KCl lean-NaCl rich deposit,withdrawing dissolved minerals through said tube, laterally developing acavity in said KCl lean-NaCl rich deposit to a desired degree,increasing the height of the cavity so developed by raising the tubevertically in increments and thereby raising its associated liner thesame increments to thereby ultimately extend the cavity into said KClrich-NaCl lean deposit, and recovering the mineral content of the KClrich-NaCl lean deposit as a solution through said tube.
 8. The method ofclaim 7 wherein said borehole is cased to a point near the interfacebetween said KCl rich-NaCl lean deposit and said KCl lean-NaCl richdeposit.
 9. The method of claim 7 wherein the initial cavity isdeveloped in a lateral direction by padding the roof of the cavity witha fluid immiscible with the cavity solution.
 10. The method of claim 7wherein said solvent is introduced through said tube and the saiddissolved minerals are withdrawn through said liner.
 11. A method ofsolution mining KCl from a KCl rich-NaCl lean deposit positioned above aKCl lean-NaCl rich deposit wherein a first cavity is positioned adjacentsaid KCl lean-NaCl rich deposit comprising drilling a borehole into saidKCl lean-NaCl rich deposit adjacent to said first cavity, casing theborehole to at least the top of the KCl rich-NaCl lean deposit, passinga tube having a liner fixedly mounted thereto and around said tubethrough said borehole a sufficient distAnce to position the lower endsof both the tube and the liner in the KCl lean-NaCl rich deposit whilemaintaining the upper end of the liner inside of said casing, the tubeand liner being so arranged that their lower ends are spaced apart fromeach other a fixed distance, introducing solvent suitable fordissolution of the mineral content of said KCl lean-NaCl rich depositthrough the liner to thereby dissolve the minerals in said deposit,withdrawing dissolved minerals through said tube, laterally developing acavity in said KCl lean-NaCl rich deposit until the cavity beingdeveloped communicates with said first cavity, withdrawing dissolvedminerals from said first cavity when the cavity being developedcommunicates therewith while using the cavity being developed as aninjection cavity for solvent, periodically raising the tube and therebyraising the associated liner in the cavity being developed a fixeddistance to increase the height of the said injection cavity, continuingthe dissolution of the mineral content of the KCl lean-NaCl richdeposit, continuing periodic raising of the tube and thereby the lineruntil the ends of the tube and liner are in the KCl rich-NaCl leandeposit and dissolving the mineral content of the KCl rich-NaCl leandeposit.
 12. The method of claim 11 wherein the flow of solvent in thetwo cavities is reversed so that solvent flows into the existing cavityand dissolved minerals are withdrawn from said cavity being developed.